Issue #3465832: Remove second check on mapId in Drupal settings; and remove...

Issue #3465832: Remove second check on mapId in Drupal settings; and remove check for existing map_data that prevents map from loading on repeated AJAX requests.

When attaching a map to a View with caching and AJAX enabled, a repeat AJAX request to refresh the view returns the same mapId. The check for an existing entry will be true which will cause loadMap() to not be called. It appears this was done to prevent the map from being loaded multiple times when lazy loading is used. Instead of checking for existing map_data, use once() to mark the map as loaded so the check is no longer needed. This allows lazy loading to work without loadmap() being called multiple times from IntersectionObserver when the map comes into view and for cached AJAX responses to refresh the map.

Closes #3465832